Monday, 11 October 2004 - 4:20 PM

This presentation is part of : Cellular Mechanics

On the dependence of DNA configurations on salt concentration

Yoav Y. Biton, Rutgers University, School of Engineering, Graduate program in Mechanics, 98 Brett Road, Piscataway, NJ 08854, Bernard D. Coleman, Rutgers University, Department of Mechanics and Materials Science, School of Engineering, 98 Brett Road, Piscataway, NJ 08854, and David Swigon, Rutgers University, Department of Chemistry and Chemical Biology, 610 Taylor Road, Piscataway, NJ 08854.

When the electrostatic interactions of the phosphate groups in a DNA molecule with N+1 base pairs are taken into account, the variational equations of mechanical equilibrium for the molecule are a nonlinear system S of 6N equations for the 6N kinematical variables characterizing a configuration. When S is linearized, the resulting 6N by 6N matrix is essentially completely full. An efficient procedure will be described for solving S and determining the stability of the resulting equilibrium configurations. The system S depends on the concentration c of salt in the water in which the DNA is dissolved. Several examples (with N of the order of 500) will be given illustrating a remarkably strong influence of the parameter c on the equilibrium configurations of intrinsically curved DNA. Moreover, several of the bifurcation diagrams presented will show regions in which more than one locally stable equilibrium configuration occurs at a single value of c.

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